A second migrant truck has been found in Austria, police said.
The truck contained 26 migrants including three children in critical condition.
Those inside were said to be from Syria, Afghanistan and Bangladesh.
Separately, four men appeared in court in Hungary following the discovery of another truck in Austria containing the bodies of 71 people.
In the latest incident, the three children were taken to hospital suffering from severe dehydration.
Police had tried to stop the vehicle near St Peter am Hart and gave chase when it drove off at speed.